Using Scala we can easily create lock free multi-threaded code, while still maintaining a familiar programming model.
There are two issues of writing multi-threaded code: synchronizing shared access to resources and running code asynchronously. In Java this is usually done with locks and implementing interfaces that wrap the asynchronous code. This leads to code that is cumbersome to write, error prone and inefficient in how it uses threads (since a thread may block for an unspecified time waiting on a lock).